[unreadable] This proposal is designed to test the hypothesis that the interaction of the chemokine receptor CXCR2 with its ligand CXCL1 regulates crucial processes for successful repair of demyelinated vertebrate CNS lesions such as those found in Multiple Sclerosis (MS) patients. First, to investigate CXCLI's influence over PDGF induced effects on adult oligodendrocyte progenitor cells (OPCS) and its modulation by HSPGs, primary spinal cord and purified oligodendrocyte progenitor cell (OPC) cultures will be compared in terms of proliferation, differentiation, and survival. Furthermore, to investigate modulations in CNS de/remyelination, lesions will be induced by injection of lysolecithin into the dorsal columns of both CXCR2 KO & WT mice expressing EGFP off the PLP promoter, which is specifically expressed in oligodendrocytes and OPCS. Temporo-spatial characterization of lesion formation and repair will be achieved by immunohistochemical (IHC), histological, and electron micrographic (EM) studies of samples derived from these animals. Finally, to determine the origin of OPCS that infiltrate and repair demyelinated lesions, to describe the molecular mechanisms underlying lesion development and repair, and to assess the efficacy of repair between adult and neonatal derived OPCS, these purified OPC populations will be transplanted to lesioned and non-lesioned KO and WT mice from which subsequently IHC and EM analysis will be performed and 3D spinal cord slice cultures developed. 3D slice cultures will allow real time visualization of cell migration via time-lapse photography and the opportunity to understand the molecular mechanisms underlying de/re-myelination. [unreadable] [unreadable]